Underwater Sunlight
by NineLaws
Summary: Kilguin Sumfest July 2016: First Topic - The Beach! Whilst looking after a patient on the seaside, Penguin is drawn to a local lagoon where he meets mermaid tail-tester Killer, who takes him for the swim of a lifetime. Penguin can't help but wonder about Killer's tail, which is apparently a machine...


**Author Notes and Review Replies will be at the end of each chapter. Disclaimer: I do not own One Piece. This is my contribution to the Kilguin Sumfest 2016! This weeks topic: The Beach! If you want to find out more or join in with this, check out: Kilguin on tumblr and you should find the blog! Anyway, hope you like this!**

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 _~Underwater Sunlight~_

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It really was too hot today. Not much fun at all for Penguin's rather fair skin that had a lovely tendency to _burn_. Sighing, Penguin figured he should at least take a moment to enjoy the view filtered with sunlight, the ocean meeting the sharp edge of the horizon and the shadow of birds gliding above. Stepping off the doorstep of his current residence, (he and his mentor Law were helping to care for an elderly man who lived along the coast, it was a special favour mostly) he hissed at the heat on his skin. Where was the damn suncream…

Law had gone out with their patient to the pharmacy but Law had also mentioned to Penguin that he wanted to give the man a helping hand around the town so he could visit some of the locals he hadn't seen in a while. Penguin smiled at the recent memory, he was lucky to have such a teacher.

With this small moment of peace, the student figured he ought to enjoy the surroundings before they returned to the city. Stepping back inside the small cottage to collect some sun-cream out of his bag and slip on some sunglasses with his yellow brimmed cap, he left the house, making sure to lock it behind him.

Across the path in front of the house was the grassy expanse upon the cliff, the edges steep around it. Penguin headed over, the grass soft beneath his shoes and he didn't dare go to close to the sides. He wasn't afraid of heights or anything but...you know, how stable are cliffs really? Even so, Penguin plucked up the courage to tread carefully down a small slope onto the lower rocks, still high above the rushing sea. The young man took a moment to inhale the salty air and smile at the calming surge of water, there was really nothing like the atmosphere of the coast. Darting over the more solid slate, he peered over the edge to see the lagoon you could see from the house. It looked even more enchanting up close, cocooned by the cliffs and a large rock protruded from the center of crystal clear water, bluer than galaxies in space.

Penguin crouched down and dared to look further, he could see the sandy ridges of rocks stepping down into the darker depths, barnacle speckled sides splashed with frothy white, glistening with such an allure Penguin wanted to go down further. It was lucky he'd worn more practical shoes than flip-flops or sandals and now scaled down the side where the rocks luckily gave him something of a natural ladder.

He wasn't yet sprayed by the surge of the ocean and wandered over the crooked edges with a chuckle on his lips. He felt like a child exploring a secret cavern. When he was finally within the lagoon itself, he marvelled at the contrast of the cool waters and the burning sky. Penguin settled down, the rocks not exactly comfortable but he didn't mind. Glancing up to the cliffs as he took off his shoes, he finally dipped his feet into the water. The chill was refreshing.

That's when it came up out of the sea. Right in front of him, perhaps two metres away. A mass of flaxen hair appeared out of the depths, falling over the eyes of a...man, but Penguin couldn't focus on his face for very long because the flash of bright blue behind him drew his attention. It was a tail! Glistening with a pattern of metallic scales, the large fins at the end lazily drooping out of the water for a moment before sliding back under. For a few seconds (probably longer which Penguin would never admit), the medical student thought:

 _Oh my god, it's a mermaid._

They both just looked at each other silently for a few moments before Penguin managed a small.

"Hi"

"Hey" was the very nonchalant reply and Penguin nearly choked. What the hell was going on?! The man seemed to realise what the man before him was going rigid at and looked back.

"Ah" he spoke, muffled under the mask and he brought his fingers up to remove the covering. Thick lips and a strong jaw were exposed and stretched a little before he spoke again.

"Before anything else happens, don't call the police or military or anything because I'm not a mermaid"

"A merman?" Penguin muttered without thinking and the blonde stopped before a grin spread over his face and he laughed.

"No, sorry" he paused and then nodded his head toward the rocky space beside Penguin.

"Mind if I sit up there?"

Penguin shook his head, still dumbfounded and he only moved to flinch at the spray of water from the man as he lifted himself up beside him and sat. Penguin would also probably not admit to eyeing those really quite powerful arms steadying himself, water shimmering off the tan flesh.

Penguin was soon staring at the tail again, even more impressive if too bright in the sunlight.

"So er...what are you?"

"A human, last time I checked" the man's voice was so dry, Penguin didn't know whether to take him seriously or not. But soon he continued talking.

I'm a...tester for 'mermaid' tails used for exhibitions and short cruises...this isn't real" the man gestured to his costume. Penguin just nodded, his shoulders relaxing. Really, what was he thinking. Mermaids?

"Sorry to startle you anyway"

"It's fine! I wasn't startled...much anyway, sorry for disturbing you"

"That's alright, I was getting out soon anyway"

"Is it hard to swim in?" Penguin couldn't help but question and the man shrugged.

"Well I test to see how easy they are, this one is pretty good. I'm a decent swimmer so it's never too much of a problem, but long term swimming in it can get kinda sore" he stretched out and Penguin still struggled to differentiate the tail from the man.

"Not many people climb down here, how come you've come anyway?"

For a stranger he was awfully chatty but Penguin didn't mind, he had a nice smile, even if the medical student couldn't see his eyes under his hair. Could the man even see him through it?

"I was bored I guess, wanted to explore a little"

"Lagoon is definitely good for that, especially when it's calm like this" the man spoke with a familiar fondness. "You going to go swimming? Today is perfect for it"

"I...I'm not really dressed for it…"

"It's warm when you're in there, but that's fine" the man shrugged again, unoffended and Penguin felt himself relax even more, this guy was really nice.

"Well...I could go get my swimming stuff, it's not far"

"Sure, if you'd like"

"A-" Penguin stopped himself and glanced away, praying the blonde hadn't heard him.

"Hm?"

Shit, he'd heard him.

"Err...nothing. I'm going to...go get my stuff now" he offered a smile and stood up carefully against the rocks. The man shrugged and just continued to sit there, shifting some of his impressive hair over to his back and Penguin gulped at the muscular mass of his torso.

It was an easy climb back to the top, the cliff being deep set with nooks and crannies he could settle his hands and feet in. Still Penguin reminded himself not to look back and down. Atop of the short cliff he looked over to the little cottage, didn't look like Law and the patient were back yet. Trudging up the slate slopes until his shoes met grass, he stood on the highest point and dared a peer over the edge. The blonde remained on the rocks, unaware of Penguin seemingly and the medical student smiled. He was going to ask whether the man was going to stay and wait for him earlier but didn't want to disturb any of his...tail trials? It sounded funny saying that and the smile remained on Penguin's face as he finally went back up to the cottage.

* * *

Penguin scrawled down a small note telling Law where he was should they come back. He mentioned that he'd also borrow his mentors wetsuit shoes for protection, they were a little big but fit fine enough. Penguin slipped off his cap and ruffled his pearly hair, cut cropped around his ears in the mirror momentarily before pursing his lips at himself and wondering why he was so concerned. Locking the door behind him once more on the way out and hiding the key under a plant pot, Penguin faced the blinding sunlight once more.

He was quicker over the grassy verge and turned into one of the narrow paths that led to a more protruding part of the cliff overlooking the lagoon. Looking over, he couldn't see the man anymore. Penguin felt his heart sink and sighed, looking down at his black and white swimming shorts and wondered whether it was even worth going in anymore, on your own it wasn't as much fun. Shifting his shoes slowly to the edge so he could look further over to see whether the stranger was swimming below, the electric sensations of nerves running up from his toes overwhelmed his body as he slipped.

It felt as though air had surged his guts upward into his throat, his body too paralysed to even flail. He barely took note of anything but the water rushing up to him. A high pitched gasp escaped him seconds before he went under. He felt himself continue sinking for a few moments before remaining suspended. Kicking up against the nothingness, hands outstretched. Panic choked him when he still couldn't feel air against his fingertips above him. Suddenly something caught him around the waist. A grip that yanked him up to oxygen and Penguin couldn't see for the water blurring his vision as he gasped.

Mindlessly gripping the body against his, the young man tread water with his desperately kicking legs below until he calmed and took a final deep breath. It was perhaps then that he wondered who the hell had managed to drag him up. Unable to loosen his trembling grip, he somewhat shook his hair from his face (where had his cap gone?) and blinked up.

Whoa the sun was seriously bright.

Oh hold on. That wasn't the sun.

Penguin didn't even think the chill of the ocean could cool the blush that raged over his cheeks as he realised he had mistaken hair for sunlight. Not just anyone's hair. It was the merman from before. Wait, not a merman, the tail-tester.

"You okay?" he asked. His voice low and soft yet nonchalant. Like he expected Penguin to be absolutely fine.

"Err...well...you know...considering...the fall…" Penguin gulped and shivered. God the water was cold. Next thing he knew the water around him surged around his spine as he was pushed backwards. The blonde was swimming toward the rocks and finally the younger man could feel limpets and stone behind his legs.

"You can let go now, you know, if you want" the man was telling him, a small smirk heard in his tone and Penguin scrunched up his face in embarrassment.

"Oh yeah, of course" he managed.

Still, there was hesitation in his actions. Despite the water around him, the man he was...attached to was seriously warm and also most likely safer than the cliffs. Even so, he couldn't exactly remain on the man so Penguin reluctantly let go. Clambering up onto the small ledges, he shuddered.

"That was quite a height"

"You're telling me" Penguin sighed. He used the excuse of looking for his cap to avert his eyes from the merman, oh wait, oh forget it. He was going to be a merman for now.

"Looking for something?" a navy hat was waved in front of his face and Penguin blinked. The older man was grinning under his mop of hair, holding up his hat.

"How did you-"

"It was floating nearby" was the quick answer, the smile never faltering as he lifted himself onto the rocks closer to plant the headwear upon Penguin's drenched hair. It only squeezed more water over his face and Penguin yelled, batting his hands away. Killer took this moment of Penguin's distraction to admire the pearly white and silver tinted locks on his head.

"Hm, so are you actually called Penguin?" the man tilted his head to the side slightly, scrutinising the label on his soggy cap. Penguin took it off and looked to it himself.

"Yeah…" his eyes widened and he then looked to the diver.

"What's your name? I can't believe I didn't properly greet you at first"

Killer smiled and answered with a series of slurred, soft letters. Penguin blinked. He took a moment before trying to work out what it sounded like.

"Ki...Killer?"

The blonde's head moved back a little in surprise but then he shrugged.

"Yeah, probably sounds most like that, it's an...unusual name"

"Oh okay" Penguin replied, feeling a little uncomfortable not knowing how to say his proper name but...Killer didn't seem too bothered.

"So are you ready to go for a swim yet?"

"Err…" Penguin looked down at his shaking limbs and grimaced.

"Maybe in a minute, don't think I'll be able to even tread water like this"

"Want a hand?" a large hand outstretched toward him in invitation and Penguin blinked down at it. Without much thought, he answered, more quietly than he intended,

"Okay".

* * *

It hadn't taken nearly as long as Penguin would have thought to relax his muscles under the support of Killer. His hand around his was unusually comforting. Penguin allowed himself to simply float on his stomach, kicking his legs leisurely as Killer swam ahead on his back, holding Penguin's hands and grinning. Whenever the younger man looked downward he could see the powerful beat of the tail shimmering under the waves. He felt the fins brush his knees and shins every now and again and shivered at how delicate they were. It wasn't like machinery at all.

They never left the lagoon which Penguin didn't mind. The water was alight like a galaxy under the sun and was much calmer in the confines of the surrounding cliffs. No one else ventured down and the privacy was...romantic. In it's own way, so surreal and beautiful.

Penguin was distracted by the rocks below, barely visible and abstract in their stony forms and could only gasp when he was pulled forward fast into the width of Killer's chest. The tail-tester surged backward into the shade of a rocky parting, his hand rested upon the back of Penguin's neck, his free arm wound around his waist. Penguin spluttered and tried to ask what was going on when he saw Killer facing the left, his mouth tight-lipped. Penguin followed his line of vision and saw some walkers up on the cliff, a middle aged couple holding hands as they strolled upon the grassy verge.

"Everything okay? Do you know them?"

Killer didn't say anything for a moment before turning to Penguin, his jaw clenched. Penguin shuddered with a pang of fear before the blonde relaxed and smiled.

"Hey, do you want to do something...different?"

Penguin raised an eyebrow.

"Like what?"

"Well...it's pretty amazing, but I'm going to have to do something first?"

"...What do you mean? Are we going to go further out to sea or something? Do I need some equipment?" Penguin's voice escalated with excitement and Killer grinned, leaning in a bit closer and Penguin's shoulders raised slightly.

"No…" Killer spoke softly. "I have to kiss you"

Penguin froze. He wished he could see the others eyes to see whether they were creased with the laughter of a joke or whether the small smile he could see was genuine.

"Is that a pick-up line?"

"No, I have to transfer oxygen to you"

 _And you can't use a machine?_ Penguin thought, he wanted to ask but at the same time. He was undeniably enchanted at the idea of kissing the merman. He was alluring enough and now there was a practical method that involved getting to kiss him? Penguin couldn't even find it within him to shake his head or refuse. Instead he managed a simple nod.

Killer perhaps seemed a little surprised but pleased and he beamed, pulling the other closer in a hug. Fingers seeping into the lower locks of Penguins hair on the nape of his neck. They curled there for a moment or two as Killer leant forward and just as Penguin could feel the warmth of his breath. He tugged ever so slightly, making the younger man shiver and then lips were upon his.

Penguin's fingertips tingled with an abnormal heat under the chill of the water as he vaguely figured where to put his hands. He settled for Killer's broad shoulders as he was further dipped. His knees settled either side of his tail. Wow that was bizarre. But Penguin was more overwhelmed with the dizzying softness of the kiss. It felt really good. His heart skipped more than one beat and he made a small gasping noise. Killer held him even tighter at that and the next thing Penguin knew was water surging up over his head and face. He didn't panic at first, just let the water slide over his skin like silken sheets. Killer stopped and moved away, Penguin sleepily opened his eyes and saw the blur of sunlight above the water.

He stared at it for a few moments, his eyes as clear as if he were above water. He didn't feel pressure under his lungs begging him for air, he didn't even feel like he was floating upwards. Suspended. Turning slowly to the side. Killer was grinning at him, arms behind his head. His hair spreading like watercolour paint spilt. His tail shifting back and forth slowly. He meaningfully opened his mouth and pointed, urging Penguin to do the same.

The younger man paused for a moment. He was mostly worried about the fact he wasn't worried. Pushing the unfamiliar feelings aside, he opened his mouth and found himself inhaling instinctively. Swiping his hands over his mouth for fear of swallowing a lungful of seawater. He was shocked to find there was no such sensation.

He looked to Kilguin questioningly but his confusion was dulled by the merman swimming up to him close again and taking his wrists gently, pulling him forward and down into the depths.

* * *

Contrary to the expected misty fog that obscured the ocean beneath the surface, Penguin could clearly see into the expanse of blue. The tiny glint of fishes like stars that escaped through his fingers, the sway of seaweed below. Greens and reds like Christmas in a washed out way. Looking down at his feet, Penguin took a moment to marvel at how warm he felt despite his initial chill. Looking further down he saw the monstrous mounds of rocks and grit his teeth at the motion of vertigo. He didn't like the idea of how far below they were despite how big they looked now. Just as he went to cradle himself in his arms, stronger arms beat him to it and hugged him.

"I know, it looks pretty weird. Kind of like looking into space"

Penguin jumped at hearing Killer speak. He turned to stare, perplexed.

"My equipment is more advanced, I wouldn't try speaking though if I were you" he shrugged. Penguin nodded, ignoring the questions swarming in his mind about this so called technology and enjoyed the feeling of being held and observing the ocean at its core.

Much like the warning of not looking down, Penguin didn't look up for fear of panicking at how far they'd come. He was easily distracted by the sway of Killer's tail as the blonde let go of him and circled him quickly before remaining suspended before him.

The tail seemed weightless, effortless to move. Even with the blending of blues about them, his tail shone with a silver gleam around the edges, accenting the small fins down the side and the spread of the fins at the end. Did he work for the one company or what? Penguin was snapped from his thoughts when Killer surged forward, speaking into his ear.

"Want to do something fun?"

Penguin just grinned, bubbles seeping from his teeth and he offered a thumbs up. Killer swam behind him and took ahold of his waist in one arm. Penguin didn't have time to purse his lips at how small he seemed in comparison as they started swimming forward. Fast.

It was only a few moments of bubble swarmed sight until Penguin was dazzled by the sunlight. They'd projected themselves out of the ocean to seemingly fly through the air. Penguin let out an excited squeal before being overcome with seawater once more. Even in the depths his grin never faded and Killer swam around to face him.

* * *

The water around them soon darkened. Briefly lit with an amorous blush of red and gold as the sun began to set. Emerging from the water, Penguin looked to the sky and felt his heart swell with a sense of peace. The day had felt like a dream. Penguin was still questioning whether he had hit his head after falling or had actually died. The sensation of a hand around his reminded him of reality and he turned to Killer who had been admiring him more than the horizon.

Such a reminder was bittersweet, he sighed looking up to the cliffs where he could see the cottage. They'd returned to the lagoon not long ago after searching out further into the sea.

"I need to go, they'll think I drowned or something" he sighed. Then chuckled. "I've done quite the opposite".

Killer's shoulders visibly dropped in disappointment but he nodded, drawing them toward the rocks where they first met.

"I'm guessing I'm not going to be able to...breathe underwater without your equipment again?" Penguin enquired, partially amused and partially curious. Killer shook his head, a smile finally on his face.

"I'm afraid not"

"...Will you be here tomorrow?" Penguin asked softly. He was momentarily mesmerised by the way the sunlight seemed to set the merman's hair alight with a coppery halo.

"Hmm...not sure" Killer answered honestly and Penguin waited, heartbeat on edge for a certain conclusion. He looked down to his feet nestled on the rocks in anticipation and was alerted by a chuckle from the blonde.

"Only if you're here"

Penguin nodded eagerly, oblivious of how childish he might seem.

"See you then, you better go up now before it gets too dark"

"Okay" Penguin nodded, still beaming. He turned up on the rocks before his eyebrows furrowed and he turned back to Killer.

"Do you need a hand with the machinery then or something?"

"No it's alright, I'm getting picked up from here very soon in a boat"

"Oh okay…" Penguin paused before dashing down and jumping into the water again, catching Killer around the neck and nearly pulling them under. He kissed him quickly and softly on the lips. At the same time he ran his fingers through his thick fringe, pulling it back and when he opened his eyes, he was met with a gaze coloured with malachite. Killer blinked at him twice.

"I thought you had to go? It's too dangerous to swim underwater at night…" he explained, a little flustered and Penguin blushed a little with a shrug.

"I-I didn't want to go swimming tonight"

* * *

Atop the cliff, Penguin looked down to where the merman sat against the rocks, waving back with a grin. The younger man then turned to the house where cosy lights were lit and he knew Law and the patient must be back. He'd already popped his sun-dried hat (he'd left on the rocks) back on. Looking back to the lagoon for a last wave, his eyebrows raised as he realised the merman had disappeared.

Wait he meant tail-tester.

Wait...

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 **A/N: I go coasteering a lot in Wales and this is based off an actual place I'll visit, the cliffs are actually way more stable and no one has ever fallen but we've jumped off some of the lower cliffs so I know what hitting water from a height is like ahahaha, I'm really enjoying the Kilguin sumfest so far! It finally got a one-shot out of me which is something of a feat since the shortest story I'll write is 3 - 5 chapters (albeit this is the same length as two and a half chapters). Hope you liked it!**

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 **~Review Replies~**

 **AriesDanger24:** Ahh, thank you my darling! I know, it's been a while since I uploaded some good old Kilguin and I'm glad you like this! Thanks so much for the review! :D

 **Leenahanwoo:** Aww thank you so much! I wanted to leave the whole "is he a merman or not?" a bit of a secret ahaha, I didn't intend to do any continuation but if you like it so much I could definitely look into it. I'm working on some other stuff at the moment and if you have any ideas I'd be really glad to take them in! I'm so happy you enjoyed this and thanks for the review!


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